Hydraulic transmission



Filed Aug. 3, 1925 3 Sheets-Sheet 1 Aug. 27, 1929. w, FERRlsy y Y 1,726,481

' HYDRAULIC TRANSMIssIoN F ed Aug. 3, 1925` 3 sheets-sheet 2 WALTEE FERR/s,

A TTORNE Y.

I N VEN TOR.

Aug. 27, 1929. w. FERRIS 1,726,481

HYDRAULIC TRANSMISS ION Filed Aug. :5. 1925 3 sheets-sheet 3 I INVENToR. Wer/ 75E Feels/5.

\ A TTORNE Y.

Patented Aug. 27, 1929.

UNITED STATES PATENToFFicE.

WALTER FE'RRIS, 0I'V IILWAUXEE,`WISCONSIN, ASSIGNOB TO THE OILGEIAB OOI- PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

HYDRAULIC TRANSMISSION.

Application led August 3, 1925. Serial No. 47,991.

This inventionrelates to variable speed powertransmissions of the type involving a pump and motor operatively connected byva hydraulic circuit.

able speeds is desirableswhen operatin are quite low.

One object of the present invention is the provision of a hydraulicl transmission in which the ump and motor are so correlated and contro ed as to provide operatin charand 18,18', groved. to removably receive a series of tangential reaction lates 19, 19". The pump disk 10- is driven by a shaft 20 keyed in the hub 11 and the motor disk 10' drives a shaft 21 ke ed in the hub .11'.

A pump cylinder arrel 22 and motor cylinder barrel 22 are arranged within the pump and motor. rings 16 and 16',-'res ectively. Each cylinder barrel is closely fitte for rotation upon an ,end 23, 23 of a pintle 24, and each is provided with a radial series of cylinders 25, 25' integral therewith, each cylinder extending substantially norma-l to one of the reaction plates 19, 19' in the rings 16, 16. A piston or plunger 26, 26', closely fitted for reciprocation in each cylinder, carries a crosshead 27 27 extending substantially parallel with and spaced from one of the reaction plates 19, 19. A set 28, 28 of rollei` elements .tween each reaction plate and crosshead acteristics best suited for a given insta lation., ermits free lengthwise reciprocation there- .Another object is the provision of a novel reversing valve between the pump and motor by which the operating characteristics may 25 be varied.

Another object is to improve the construction vand operation of hydraulic transmissions.

Other objects and advantages will appear 30 from the following description of an illustrative embodiment of the present invention.

In the accompanying drawings:

Figure 1 is a vertical sectional lview of Ia hydraulic .transmission constructed in accordance with the present invention.

Figure 2 is a horizontal sectional view.

Figure 3 is a transverse sectional view taken substantially alongthe'line 3-3 of' Figure 1. l Figure 4 is a sectional view of a reversing 40 valve.

the two positions of the valve.

Figure 5 is a development of the c lindrical valve seat, dia ammatically in icatin'g the arrangement o valve ducts and ports in tweenv and 4reacts under the transmitted pressure to maintain these parts in arallelism. Each cylinder 25, 25 is provi ed with a port 29,- 29' adapted to register successively with orts 30, 30 and 31, 31' in the ends 23,

23 o the lpintle durin rotation of the cylin# der ybarre thereon. orts 30 and 31 com.- municate, respectively, with upper and lower pairs'bf passages 32 and 33 in the pump end of the pintle and ports 30 and 31' with upper and lower pairs of passages 32 and 33 in the motor endof the pintle. Pump and motors oflthis t pe are now well known in the art so that a urther or more detailed description thereof is deemed unnecessary.

In the transmission shown a valve is ememployed for eifectin and controllingzcommunication between t e pintle passages 32, 32', v33 and 33. v In this instance, this valve comprises a collar 34having a cylindrical inner surface 35 ,'closely fitted for rotation upon the cylindrical surfacej36 of the pintle 24 intermediate the ends. thereof. The cylindrical lsurface 36 is pierced by four equally l s aced' orts 37, 38 arranged ina circle about t e pin e and a similar series of ports 37",38

spaced'from ports 37, 38. Both of the upper ports 37 communicate with bothcof the upper pintle passages 32 through an angular passage 39, and both of the ower vports 38com municate with-both of the lwerpintle passages 33 through an angular passage 40. Similar passages 39' and '40' eifect communication betweenports 37' and passages 3.2 and 37, 38 while the other end is adapted to register with one or another of the series of ports 37', 38. The arrangement is such that when v the valve collar 34 is in the position shown in Figure 3 channel 41 connects one of the ports 37 with one of the ports 37 and channel 42 connects one of the ports 38 with one of the ports 38'. In this position of the valve fluid delivered from the pump through passages 32, passes throughpassage 39 and oney of the ports 37, into and through the channel 41, (in the full line position of Figure 5) and through one of the ports 37', passage 39 and passages 32' to the motor to operate the motor in one direction. Fluid discharged from the motor returns to the pump through passages 33', passage 40', port 38', channel 42, port 38, passage 40 and assages 33.

By .rotating tiie valve collar 34 through an angle of ninety degrees into the position shown in Figure 4 channels 42 and 41 assume the dotted line ositions of Figure 5. In this position, fluid elivered from the pump into passaves 32 passes through passage 39 and port 3 ,into and through channel 42, through port 38', passage-40' and passages 33 to the motor to operate the motor in the reverse direction. In this position of the valve fluid discharged from theV motor returns to the pump through passages 32', passage 39', port 37', channel 41, port 38, passage 40 and passages 33. It will thus be noted that reversal of the motor may be effected by shifting the valve from one -to the other of the two positions indicated.

It 'is a well known fact that the fluid displacement of a pump or motor of the type herein illustrated is directly proportional to the distance between the axes of rotation of the disk 10 or 10 and the cylinder barrel 22 or 22. Thus in the case of the pump when the axes of rotation of the pump disk and cylinder barrel are coincident pum displacement is zero, and, when one axis is aterally offset with respect to the other, the rate and direction of fluid flow from the pump is dependent upon the degree and direction of this offset or eccentricity. It is also recognized that for a ven operating pressure the torque delivered the motor is proportional to'the degree of eccentricity of the axes of rotation of the motor -disk and cylinder barrel.

In the hydraulic transmission shown provision is made for varying the displacements of pump and motor simultaneously and in a ldefinite predetermined relation, so that-with a given pump speed and operating pressure the motor torque and speed may be varied according to a definite law best suited for a given commercial application. In this 1n.- stance, the axes of rotation --m and of the pump and motor disks 10 and 10', respectively, are fixed and permanently offset as indicated in Figure 2. y The pintle 24 is a substantially straight rigid member so thatv the axes of rotation of the pump and motor cylinder barrels 22 and 22' coincide with the longitudinal axis y-y thereof. The pintle is horizontally movable, however, so as to shift the axis yy relative to the axis wand f-'-, and for this purpose is'secured in an upright frame 43 rockably supported upon a horizontal shaft 44 fixed in the bottom ofthe casing 15. This frame is suitably fashioned end 51 with a control rod 52. The arm 49 is of sufficient length and so disposed that the valve 34 is not appreciably affected by the rocking action of the frame 43.

For purposes of illustration, let it be assumed that the distance between the axes of rotation :zz-m and w'-m' of the pump and motor disks is one half of an inch and that the pintle is horizontally movable so as to shift the axis y-y thereof from an intermediate position, coincident with the pump' axis :v4-a1,

to either side thereof, a distance equal to one quarter of an inch. Thus, during the` movement of the pintle from one extreme position to the other the distance between the motor axes -w and y-g/ varies from one quarter to three quarters of an inch, while the distance between the pump axis www and g/y varles from one quarter of an inch m i" one d1rect1on-to one quarter of an inch 1n y the opposite direction. In other words, during movement of the pintle between its two extreme positions the stroke of the motor pistons varies from a minimum of one half inch to a maximum of an inch and a half and simultaneously, the stroke of the pump piston varies from a maximum of one half inch to zero and then from zero stroke to a maximum of one half inch, reversing the direction of Huid 'low as the pintle passes through zero stroke position.

Let it be assumed that the pump is driven at constant speed in one direction by the shaftl in Figure 2 with the pintle axis y-y in one extremel position between the axes --w and -20 and that the parts are in the position shown aff-ac. In i this position of the parts, the pump is at maximum stroke and the motor at minimum stroke. Under these conditions the motor operates at maximum speed and applies a minimum torque to the shaft 21. This is an ideal condition for effecting a high speed return stroke of a driven reciprocating member. Then as the pintle is shifted fro-m this position in such direction that the axis y-g/ thereof approaches the axis of the pump the motor stroke is increased and the pum-p stroke simultaneously decreased, thus causing a very fast reduction' in motor speed until the axis y-g/ coincides with axes mat whichtime the motor comes to rest. Adjustment of the. pintle in this direction effects an increase in motor torque. As the pintle is shifted further in the same direction from that position in which the axis y-y coincides with the axis :r-- both the motor and pump strokes increase with the result that the torque of themotor increases and the motor operates at'increasing speeds in the opposite direction. This is a condition best suited for producing a working or feeding stroke of a driven reciprocating member.

In the transmission shown the operating characteristics thereof -may be modified by shifting the valve 34. Thus, by shifting this valve during adjustment of the pump through zero stroke position the `motor may be made to operate in one direction only, instead of reversing at the time of pump reversal.

Various changes may be made in the embodiment of the invention hereinabove specifically described, Without departing from or sacrificing any of the advantages of the invention as defined in the appended claims.

I claim:

1. A hydraulic transmission unit comprising a variable stroke pump including a series of piston and cylinderV assemblies grouped about a center, a variable displacement motor, including a lseries of piston and cylinder assembli'es grouped about a center and having a greater maximum stroke than the pump, a member extending from the center of the pump to the center of the motor and movable to simultaneously vary the stroke of both, and passages in said member forming hydraulic connections between said pump and motor.

- 2. A hydraulic transmission unit comprising a variable stroke pump, a variable stroke motor having a greater maximum stroke than the pump, a member having fluid passages connecting said pump and motor and movable -to simultaneously vary the stroke-of both,'and

means for moving said member to. vary the stroke of the pump through zerol stroke position without reducing the stroke of the motor to zero.

3. A variable speed transmission unit comprising a casing, a variable displacement pump therein, a variable torque motor therein of greater capacity than said pump, a member ronnections between said pump and motor,

and an adjustable support for the other member of the pump and the other member of the motor movable to shift the axes of rotation thereof relative to said fixed axes.

5. In afhydraulic transmission the combination of an adjustable support, a pump having a rotary member mounted on said support and a second coacting member rotatable about a fixed axis, a motor having a rotary member mounted on said support and a second coacting member rotatable about a fixed axis offset froml said first named axis, and means for adjusting said support.

l6. A hydraulic transmission comprising a variable displacement pump, a hydraulic motor, a member having passages ycommunicating with the pump and passages communicating with the motor, means for moving said member to vary the stroke of the pump, and a valve on said member controlling communication between said passages to reverse said motor.

7. A hydraulic transmission comprising a variable displacement pump, a variable torque motor, a member movable to simultaneously vary pump dis lacement and motor ltorque, control means or said member, passages in said member communicating with said pump, passages in said member communicating with said motor, and valve mechanism controlling communication between said passages to reverse said motor.

8. In a hydraulic transmission the combination of a variable stroke pump, a variable stroke motor driven thereby, a member connecting said pump and motor and movable to A regulate the stroke thereof, fluid passages in said member communicating with said pump and motor, and a valve associated with said member for controlling said passages to renamed passages selectively to thereby reverse said motor;

5 motor and movable to simultaneously vary the displacement of both, said motor having a Wider range of adjustment than said pump to permit a full range of adjustment of said pump through zero stroke position Without 10 reducing the displacement of said motor to zero. I

. 11. A hydraulic transmission comprising a reverslble flow. variable dlsplacement pump, a

variable displacement motor, hydraulic driving connections betweensaid pump and motor, and means for simultaneously varying the displacement of said pump and motor to vary the speed and torque of said motor, said motor havingr a greater range of adjustment than `said pump to thereby ermit a fullrange adjustment of said pump tlirough zero stroke position' without reducing motor stroke to zero.

In witness whereof, I hereunto subscribe my name this 13th day of February, 1925.

WALTER FERRIS 

